Help with piano homework

[ShEv]

My piano teacher gave me a new piano assignment for playing 3-part Bach Fugues.  She wants me to interchange the voices before putting the entire piece together.  My assignment is to play the soprano and alto voice, the soprano and bass voice and the alto and bass voices.  I am having a tough time with this because I can't just play the two voices without having to write in the appropriate fingerings that are going to be used to play the piece.  To me, it doesn't make sense to just play the voices with fingerings that are not going to be used to play the piece.  It's confusing me because in Bach fugues, you will often use the left hand to play the alto and base, the right hand to play the soprano and alto, etc.  to keep a continuous legato line.  I have become so frustrated with this assignment that I don't want to even look at another fugue.  Any suggestions for tackling this assignment?  You can email me at ShnEvt@aol.com.  

[88keys]

Indeed it seems to make little sense...

Why don't you ask your teacher WHY she asked you to do this? This would affect the way you should approach the excersice.

If the idea here is that to get you to know the music itself better, than there is nothing wrong with using different fingering or alternating hands.

If, on the other hand, there is some technical point in the excersice, the above would be a bad idea.

In any case, you are certainly entitled to know what's the point of the excersice you are given. If the teacher refuses to explain this to you, perhaps you should consider a different teacher.